In FM receivers, harmonic distortion is caused in an FM demodulation signal due to the frequency vs amplitude and the frequency vs phase characteristics of a band-pass filter in an intermediate frequency (IF) amplifier circuit. This harmonic distortion is mixed by a stereo MPX circuit and exerts distortion to the right and left channel signals, respectively. On the other hand, in FM receivers of higher grade, some of them are provided with a wide band IF amplifier and a narrow band IF amplifier and select one of the wide band and the narrow band in accordance with the receiving conditions. In such receivers, the degrees of harmonic distortions differ in the cases of wide band and narrow band.